Game only launches once — second launch stuck on “Download Game Data”

[Assassin286]

Moonfin version

2.3.1 issue was in 2.3.0 also

Platform

Windows

OS version

LMDE 7 also in iOS (all versions)

Device model

No response

Input method

Other / not sure

Server type and version

Jellyfin 10.11.11

Content type

Other

Media details (as much as you know, check the info button at the bottom right of the player)

I tested this directly through the Jellyfin IP as well, without nginx:

http://xxxx:8096/Moonfin/Web/

The behaviour is the same on web and iOS: the game launches correctly the first time, but after exiting, the second launch gets stuck.

In the Windows client, it gets stuck at “Download Game Data” without showing any percentage.

If I open Moonfin in an incognito/private window, the game works again because the game files are downloaded from scratch.

Through the normal browser session I was able to capture:

HEAD /Moonfin/Games/... --> 405 Method Not Allowed

followed by:

TypeError: Cannot read properties of undefined (reading 'content-length')

Since it also happens through the direct Jellyfin IP, nginx should be ruled out. It looks like the first uncached download works, but loading the already cached game data on the next launch fails. Could this be related to the new EmulatorJS changes or the HEAD request not being supported by the game endpoint?

Playback path

Not sure

Symptoms (check all that apply)

• Black screen / endless spinner
• Audio only (no video)
• Stuttering / frame drops
• A/V sync issues
• Seeking/scrubbing broken
• Subtitles missing or incorrect
• Unexpected forced transcode
• App crashes / exits

Steps to reproduce

1. Open Moonfin Web or the Moonfin client.
2. Start any Retro Game.
3. Wait for the game files to finish downloading.
4. Confirm that the game starts normally.
5. Exit the game using the emulator’s Exit option.
6. Start the same game again.
7. The loading screen gets stuck at “Download Game Data” without showing a percentage.
8. Open Moonfin in an incognito/private window.
9. Start the same game again.
10. The game works once because the game files are downloaded again.
11. Exit and start it a second time in the same private session.
12. It gets stuck at “Download Game Data” again.

Frequency

Always

Logs / errors (optional)

No response

[RadicalMuffinMan]

The game type would help narrow this down since there are multiple platforms and the cores are not the same, as well as more complete error logs.
Settings > About > Debugging
Repeat actions then return to debugging and submit the log to your server

[samiam567]

upload_Moonfin for Web_2.3.1_20260729235812_2fd2c9d509a24d3bb80558ef574ffc59.log

Experiencing the same issue. This is LEGO Batman - The Videogame from the nds core. I have this issue with other games, but the nds core may be the primary culprit

This seems to be the primary error:

http://192.168.1.114:8096/Moonfin/Games/Saves/XFwxOTIuMTY4LjEuODJcYWxlY3Jhc3BiZXJyeXBpbmFzXE1lZGlhIFNlcnZlclxHYW1lc1xMZWdvXExFR08gQmF0bWFuIC0gVGhlIFZpZGVvZ2FtZSAoVVNBKSAoRW4sRnIsRXMpLm5kcw?kind=state (404)
└─ This exception was thrown because the response has a status code of 404 and RequestOptions.validateStatus was configured to throw for this status code.
The status code of 404 has the following meaning: "Client error - the request contains bad syntax or cannot be fulfilled"
Read more about status codes at https://developer.mozilla.org/en-US/docs/Web/HTTP/Status
In order to resolve this exception you typically have either to verify and fix your request code or you have to fix the server code.